Al and Ben are drivers for SD Trucking Company. One snowy day, Ben left SD at 8:00 a.m. heading east and Al left SD at 1

[Vincen]

Al and Ben are drivers for SD Trucking Company. One snowy day, Ben left SD at 8:00 a.m. heading east and Al left SD at 11:00 a.m. heading west. At a particular time later that day, the dispatcher retrieved data from SD’s vehicle tracking system. The data showed that, up to that time, Al had averaged 40 miles per hour and Ben had averaged 20 miles per hour. It also showed that Al and Ben had driven a combined total of 240 miles. At what time did the dispatcher retrieve data from the vehicle tracking system?

A. 1:00 p.m.
B. 2:00 p.m.
C. 3:00 p.m.
D. 5:00 p.m.
E. 6:00 p.m.

Answer: B

Source: Official Guide

[Brent@GMATPrepNow]

Al and Ben are drivers for SD Trucking Company. One snowy day, Ben left SD at 8:00 a.m. heading east and Al left SD at 11:00 a.m. heading west. At a particular time later that day, the dispatcher retrieved data from SD’s vehicle tracking system. The data showed that, up to that time, Al had averaged 40 miles per hour and Ben had averaged 20 miles per hour. It also showed that Al and Ben had driven a combined total of 240 miles. At what time did the dispatcher retrieve data from the vehicle tracking system?

A. 1:00 p.m.
B. 2:00 p.m.
C. 3:00 p.m.
D. 5:00 p.m.
E. 6:00 p.m.

Answer: B

Source: Official Guide

Let's start with a "word equation"

(Ben's travel distance) + (Al's travel distance) = 240 miles

Let t = Al's travel time (in hours)
So, t + 3= Ben's travel time (since Ben spent 3 more hours driving)

Distance = (rate)(time)

So, our word equation becomes...
(20)(t + 3) + (40)(t) = 240 miles
Expand: 20t + 60 + 40t = 240
Simplify: 60t + 60 = 240
Subtract 60 from both sides: 60t = 180
Solve: t = 3
So, AL traveled for 3 hours (which means BEN traveled for 6 hours)

So, the dispatcher retrieved data at 2pm (since 8am + 6 hours = 2pm)

Answer: B

Cheers,
Brent

[Scott@TargetTestPrep]

Al and Ben are drivers for SD Trucking Company. One snowy day, Ben left SD at 8:00 a.m. heading east and Al left SD at 11:00 a.m. heading west. At a particular time later that day, the dispatcher retrieved data from SD’s vehicle tracking system. The data showed that, up to that time, Al had averaged 40 miles per hour and Ben had averaged 20 miles per hour. It also showed that Al and Ben had driven a combined total of 240 miles. At what time did the dispatcher retrieve data from the vehicle tracking system?

A. 1:00 p.m.
B. 2:00 p.m.
C. 3:00 p.m.
D. 5:00 p.m.
E. 6:00 p.m.

Answer: B

Source: Official Guide

Solution:

Let t represent the time that passed between the departure of Al (11:00 a.m.) and the retrieval of data by the dispatcher. Since Ben left at 8 a.m., his time is (t + 3). Since their combined distance was 240 miles, we can use the formula distance = rate x time and create the following equation:

Ben’s distance + Al’s distance = 240

20(t + 3) + 40t = 240

20t + 60 + 40t = 240

60t = 180

t = 3 hours

Thus, it was 11 a.m. + 3 hours = 2 p.m. when the dispatcher retrieved data from the vehicle tracking system.

Answer: B